1. Technical Field
The present invention relates to a battery module and, more particularly, to a battery module having a plurality of unit batteries and interposed barriers.
2. Related Art
Unlike a primary battery, the rechargeable battery may be recharged. Lower power batteries are used for various portable electronic devices such as cellular phones, laptop computers, and camcorders. Bulk size batteries are used as the power source for motor drive, such as in hybrid electric vehicles.
Depending on the external shape, rechargeable batteries may be classified into different types, for example, prismatic and cylindrical batteries. When they are used for motor drives for machines requiring a high power source, such as the hybrid electric vehicles, the rechargeable batteries may form a battery module of high power.
The battery module is formed by serially connecting several rechargeable batteries (hereinafter “unit batteries”), and each of the unit batteries includes an electrode assembly in which a separator is interposed between a positive electrode and a negative electrode. The electrode assembly is inserted inside a case, and a cap assembly is assembled with the case to seal the case. The cap assembly can include terminals which are disposed so as to extend from the inside to the outside of the case, and which are electrically connected to the positive electrode and the negative electrode, respectively.
If the unit batteries are prismatic type batteries, the unit batteries are arranged so as to alternate positive and negative terminals of one unit battery projected from the upper portion of the cap assembly with the positive and negative terminals of an adjacent unit battery. Adaptors of the electric conductor are typically mounted on the threaded negative and positive terminals so that they are electrically connected with each other to form the battery module.
Since the battery module connects several to tens of unit batteries to form one battery module, there is a need to efficiently dissipate heat generated from each unit battery. In particular, when the unit batteries are used as bulk size rechargeable batteries for a motor drive, such as in electric vehicles, hybrid electric vehicles, motor scooters, and vacuum cleaners, heat dissipation is of significant importance.
If heat dissipation does not occur properly in the battery module, the temperature of the battery module may increase excessively due to the heat generated from each unit battery, and accordingly, not only the battery module but also the machines with the battery module can malfunction.
Accordingly, when forming the battery module, a barrier is disposed between unit batteries, and the space formed by the barriers between the unit batteries is used not only for cooling the unit batteries, but also for preventing distortion due to heat expansion of the unit batteries.
To perform such functions, the barrier needs sufficient strength, and structure for efficient heat dissipation.
However, the barriers in the conventional battery module do not satisfy the above two conditions simultaneously so that there is difficulty in forming battery modules of the quality which consumers expect.
That is, if the barriers provide sufficient strength, the manufacturing cost is increased and there is a restriction in designing a passage of cooling air. Alternatively, if the barriers are formed so as to have high cooling efficiency, they tend to exhibit structural weakness.